This invention relates to the field of track roller bearings, and particularly to the field of track roller bearings having a self-lubricating material on one of the races of the track roller bearing. More particularly, this invention involves an improvement in the construction of axial thrust bearings of a track roller bearing.
Track roller bearings, and particularly track roller bearings having a self-lubricating liner or bearing material, are well known in the art. When originally introduced, and for many years thereafter, self-lubricated track roller bearings had the self-lubricating liner material bonded to the inner surface of the outer race. Examples of such self-lubricated track roller bearings are disclosed in U.S. Pat. Nos. 4,048,370 and 4,134,842, the disclosures of which are incorporated herein by reference.
A very important improvement in the construction of self-lubricated track roller bearings is disclosed in U.S. Pat. No. 4,717,268, wherein the self-lubricating liner or bearing material is secured to the outer surface of the inner race. The construction of U.S. Pat. No. 4,717,268 resulted in a track roller bearing having the advantage of significantly extended bearing life relative to track roller bearings in which the self-lubricating material was secured to the inner surface of the outer race. U.S. Pat. No. 4,717,268 is assigned to the assignee hereof, and the disclosure thereof is incorporated herein by reference.
All of the self-lubricating bearings discussed above have side rings perpendicular to the axis of the bearing and perpendicular to the primary load bearing faces of the inner and outer races. These side rings are connected to the inner races, and the side rings serve both to lock the inner and outer races together and to absorb axial thrust loads in the bearing, i.e., loads in the direction of the axis of the bearing and perpendicular to the direction of the load normally imposed on the inner and outer races of the bearing. These side rings face and oppose flat areas on opposite sides of the outer race which are perpendicular to both the axis of the bearing and to the bearing face of the outer race. As disclosed in, e.g., U.S. Pat. Nos. 4,134,842 and 4,717,268, while one of the side or thrust rings may be integral with the inner race, the other ring is a separate element which is attached, e.g., by welding or press fit, to the inner race after the inner and outer races are assembled. Thus, self-lubricated track roller bearings of the prior art require at least three separate elements (four if the self-lubricating bearing liner is counted as a separate element); and at least one of the side rings must be welded or otherwise secured to the inner race after the bearing is assembled. This is undesirable because the requirement for separate ring parts and the processing to attach the rings results in increased costs for the bearing. Also, if self-lubricating material is to be used the axial thrust elements, it is applied in separate rings to the flat surfaces on the outer race opposing the side rings (see, e.g., U.S. Pat. No. 4,717,268). This, too, adds to the cost of the bearing.
An example of a self-aligning track roller bearing having self-lubricating material on the outer diameter of the inner race is shown in U.S. Pat. No. 4,842,424, the entirety of which is also incorporated herein by reference.